Numerical Study of Gas Phase Flow in Cyclones with the Repds

Experiments have shown that a cyclone's energy loss can be largely reduced by a stick called a Repds (Reducing Pressure Drop Stick). The present study reports on a three-dimensional numerical simulation performed using FLUENT, a kind of computational fluid dynamics (CFD) software. The simulation result confirmed the effectiveness of the Repds in reducing the energy loss. This article compares the numerical results with two sets of experimental results. The numerical calculation shows that the Repds reduces the tangential velocity peak and increases the axial velocity in the central region of the cyclones. The change in the velocity distribution results in the reduction of the energy dissipation in the cyclones.     

An efficient method for the enrichment of the arachidonic acid methyl ester from Mortierella alpina-derived crude oils

An improved method was developed for enriching arachidonic acid (AA) methyl ester from microbial oil by two-step low-temperature wet fractionation. The effects of solvent, operating temperature, and solvent-to-fatty acid methyl esters (FAMEs) ratio on the enrichment of AA were investigated. The best results were achieved when n-hexane was used as solvent. With operating temperatures in the range ?30 °C to ?80 °C and a FAMEs-to-solvent ratio of 1:5 (v/v), the proportion of AA methyl ester isolated could be increased to 83.76 ± 2.78% with a yield of 52.89%. The total recovery of AA methyl ester would be further increased to 90.84% by recrystallization of the solid phases. The 20C, 22C saturated fatty acids were enriched by n-hexane or petroleum ether at ?30 °C, with concentrations increased 7.5-fold or 7.2-fold compared with their original levels, respectively. In addition, a method that combined alkali and acid catalysis of the transmethylation was the most conducive to the preparation of polyunsaturated fatty acid methyl esters.     

射频溅射沉积SiO2膜的工艺及其结构性能研究

利用自制的磁控溅射沉积设备,针对影响SiO2薄膜沉积速率的氩气流量,氧气分压两个关键参数进行工艺研究,并通过扫描电子显微镜(SEM)对沉积完成的Si不O2薄膜表面、剖面结构质量进行表征,结果表明,射频溅射沉积的SiO2薄膜均匀、致密,具有良好的结构性能.     

试析人民币内外价值背离的新货币现象

近年来,随着我国经济持续快速增长,外汇储备屡创新高,人民币对外升值的幅度不断增大;与此同时,人民币在国内按购买力计算的对内价值趋于下降,人民币的内外价值走向出现差异,并有不断扩大的趋势.人民币对内升值和对外贬值已经成为一种新的货币现象.     

Rapid preparation of CuInS2 microparticles via a solution-chemical synthesis route and its characterization

CuInS₂ microparticles were synthesized successfully by a facile solution-chemical method in a mixed solvent of triethylenetetramine–ethylene glycol (1:1, v/v) under the open-air condition using copper chloride, indium chloride and sulfur as starting materials. The factors including the temperature and reaction time which might affect the purity of the product during the synthesis were discussed. Phase constituents, morphology, structure and optical properties of the as-prepared CuInS₂ powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectrometer (EDS), and ultraviolet–visible (UV–vis) spectrophotometry. It's found that the products were significantly affected by the temperature and reaction time. A possible formation mechanism was put forward and briefly discussed.     

Study on the Effect of Cure Cycle on the Process Induced Deformation of Cap Shaped Stiffened Composite Panels

Cap-shaped stiffened composite panels offer many excellent properties such as low density, high strength, high stiffness to weight ratio, and design flexibility. During their manufacturing processes, however, thermo-curing inherently produces the undesired residual stresses and cure deformations, which limits the applications of composite structures in a certain degree. In order to reduce the cure deformation, in this paper, the effect of cure cycle (curing temperature, curing pressure, cooling rate) on the process-induced deformation of cap-shaped stiffened composite panels was presented. A simple mathematical model based on the curing dynamics was established to predict the deformation of the cap-shaped stiffened composite panels. The deformation calculated by the mathematical model and experimental studies were compared, and an Error Correction Model was established. The Error Correction Model showed a good agreement with the experimental results.     

Room Airflow Studies Using Sonic Anemometry

Abstract To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s^?1 to 9.7 cm s^?1. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s^?1 to 35.5 cm s^?1 with turbulence intensities from 33% to 108%.     

钢-玻混合结构采光顶的设计应用

介绍深圳某商场采光顶工程采用钢一玻混合结构的设计过程，包括面玻璃、玻璃肋、支承钢结构等的设计与受力分析等．供设计人员参考。     

模糊诊断模型在立体仓库故障诊断中的应用

介绍了模糊诊断模型，并利用该模型对立体仓库的关键设备－巷道堆垛机故障进行了诊断，结果表明，模糊诊断是机械故障诊断的一种有效方法。     

创新农村移民安置方式研究

水电建设涉及的移民主要是农村移民。随着国家经济建设的快速发展,我国人地矛盾凸现。以大农业安置为主要手段的传统水电建设移民生产安置方式受到挑战。一些电站项目开始了探索新的移民安置方式的尝试。为此,就创新农村移民安置方式,以"以人为本,平稳过渡"的原则,对有关土地政策、安置模式设计等进行了较深入的研究,提出了有助于提高移民直接收入和长久生计保障的可持续发展补偿安置建议。